Endocrine Abstracts

Introduction: Higher body mass index (BMI) has been associated with adverse renal outcomes, including chronic kidney disease (CKD), progression to end-stage renal disease (ESRD), nephrolithiasis and renal cell cancer. Several studies have shown that weight loss following bariatric surgery has a positive effect on kidney function, mediated by a reduction in proteinuria, glomerular hyperfiltration and improvements in blood pressure and insulin resistance. The aim of this study was to examine the changes in estimated glomerular filtration rate (eGFR) in a group of morbidly obese patients 6 months after laparoscopic sleeve gastrectomy (LSG).

Materials and methods: 221 severely obese patients (65.2% women, mean age=41.97±11.24 years, mean BMI=44.7±8.57 kg/m²) underwent a complete clinical and biochemical assessment before and 6 months after LSG. The variation of parameter values(Δ) was expressed in percentages out of the preoperative values. Kidney function was calculated using the MDRD-4 formula.

Results: Of the 221 patients, 53.4% were hypertensive, 25.4% had diabetes and 53.8% presented with metabolic syndrome (MetS). Six months after surgery BMI declined to 31.84±6.7kg/m² (P<0.001) and an excess weight loss (EWL) of 73.86±30.33% was observed. In addition, the prevalence of CKD risk factors decreased significantly to 34.3%, 8.5% and 14% for hypertension, diabetes and MetS respectively (P<0.001). Regarding the kindney function, 71.5% of patients had an eGFR lower than 90 ml/min/1.73 m², with mean eGFR=82.15±18.50 ml/min/1.73 m². Postoperatively, eGFR increased to 86.33±20.4 ml/min/1.73 m² (P<0.001) and 60.2% had an eGFR <90 ml/min/1.73 m² (P<0.001). Negative correlations were established between ΔeGFR and ΔBMI (r=−0.195, P=0.004), Δcalcium levels (r=−0.273, P=0.038). Patients were further examined after being separated by baseline eGFR (<90 and >90 ml/min/1.73 m²). Comparing the two groups, the patients from the eGFR<90 group were older (44.03±10.09 vs 36.81±10.2 years, P<0.001) and had a lower BMI (43.69±7.97 vs 46.8±9.6 kg/m², P=0.014). While a slight increase in eGFR was noticed in the <90 group (73.29±10.38 preoperatively vs 79.28±15.87 ml/min/1.73 m² postoperatively, P<0.001), there was no change in the >90 group (104.38±15.48 preoperatively vs 104.02±20.13 ml/min/1.73 m² postoperatively, P=0.068).

Conclusion: Bariatric surgery is an effective method of improving CKD risk factors such as hypertension and diabetes and weight loss is associated with an increase in eGFR in patients with renal impairment.